1. Technical Field
The present invention relates to a retractable suspension system for an amphibious vehicle, the suspension system being able to be raised when the vehicle is floating in water and lowered again prior to the vehicle being beached.
2. Related Art
Amphibious vehicles having retractable suspension systems are known, for example, from WO93/15923. In prior art suspension systems the suspension is held in the lowered or retracted positions by means of either a hydraulic ram, for example, or by utilisation of the weight of the suspension system itself. However, hydraulic cylinders can fail and using the weight of the suspension system itself can be problematic especially when the vehicle is in the water and being subjected to rough weather pounding.
Thus it is an object of the present invention to provide a suspension system which may be locked in the lowered or retracted positions without having to rely upon hydraulic cylinders or inertia forces due to the suspension mass.
According to the present invention, there is provided a suspension system for an amphibious vehicle, the suspension system being able to be locked in either a lowered or in a retracted position according to whether the vehicle is on land or in water, respectively, the suspension system comprising: a main suspension arm pivoted to a vehicle hull at one end thereof, the arm having a rotatably mounted road wheel thereon at an opposite end thereof. A moving mechanism is operably attached to the pivoted main suspension arm to enable the arm and the road wheel to be retracted relative to said hull. An upper suspension link is operably and pivotably connected to the road wheel end of the main suspension arm and has a pivoted joint intermediate its ends. The upper suspension link is pivoted on the hull at an axis remote from the pivoted joint. The upper suspension link is operably engagable with a suspension position locking mechanism in both the lowered and retracted positions.
In this specification the term xe2x80x9chullxe2x80x9d is used to denote any part of the body of the vehicle on which the suspension system according to the present invention is mounted or interacts with. The suspension arms and links may not be directly pivotally mounted onto the hull but may be mounted on sub-frame or bracket means, for example, which sub-frame means are mounted on the hull. In this way whole suspension units may be attached to a hull rather than in piecemeal fashion. The term xe2x80x9chullxe2x80x9d thus includes suspension units or components fixed either directly to the vehicle hull or indirectly to the vehicle hull by sub-frames, brackets and the like.
The term xe2x80x9csuspension systemxe2x80x9d as used herein in its broadest sense denotes the running gear which is retractable and lowerable and on which the vehicle rests and travels when on land. Thus, in its broadest sense the term xe2x80x9csuspension systemxe2x80x9d need not include suspension springs and shock absorbing means.
In a preferred embodiment of the present invention, the suspension system according to the present invention further includes spring and shock absorbing devices.
The spring device may be any suitable device such as coil springs and/or torsion bars for example. The shock absorbing device may also be any type suitable for the application such as telescopic dampers or lever arm shock absorbers or any known system which is suitable, for example.
The moving mechanism may be selected from any that is suitable for the application such as hydraulic or pneumatic cylinders, ball-screw type actuators, chain or belt drives, for example.
The suspension raising and lowering mechanism may alternatively be in the form of a torsion bar rotating about the axis where the main suspension arm, or the axis where any other suspension arm, is pivoted to the hull. In such cases, the torsion bar may also act as the road-going suspension spring.
The suspension system according to the present invention is suitable for a rear, non-steering suspension or, with the addition of a swivel hub at the road wheel to main suspension arm junction, a steerable suspension system may be provided.
A drive mechanism may also be provided to the road wheel by any suitable means such as by articulated drive shaft to the road wheel or by belt or chain drive means to the road wheel.
The suspension position locking mechanism may comprise mechanical means which operably engage with the upper suspension link to prevent further movement of this component when in either of two extreme positions resulting from the suspension system being lowered or retracted.
When being lowered or raised, the wheel of the suspension system generally moves in the plane of the wheel, i.e. normal to the axis of rotation thereof.